The Biostatistics Core will provide biostatistical collaboration and computer system support for the four UW STD-TM-CRC projects described in the current application. In addition the Biostatistics Core will support trainees, fellows and STDCRC New Investigator Award recipients. Specifically, the Biostatistics Core will 1) provide statistical collaboration and consultation on study design; forms design, evaluation and pretesting; data analysis; interpretation and reporting; and coordinate Data Safety and Monitoring boards; 2) provide statistical and data management leadership and coordination among the STDCRC projects and between the STDCRC and other groups conducting STD/HIV research at the University of Washington; 3) serve as a liaison between core users with advanced statistical needs and statistical experts from the UW Department of Biostatistics; 4) develop, adapt and/or implement new or novel statistical methods as needed; 5) maintain computing facilities which are available (both on site and by remote login) to any investigator; 6) provide management of the Data Sharing Plan for the STI TM CRC. In addition, the Core will collaborate with the Biostatistics Core of the NIH-funded UW Center for AIDS Research to promote interactions and collaboration among biostatisticians and epidemiologists involved in federally funded STD and HIV-related research at the UW.